| In this study,mitochondrial COI gene?cytochrome b(Cytb)and control region(D-loop)sequences as well as genomic microsatellite markers were used to analyze the genetic diversity,genetic structure,and population history of eleven Scomber japonicus populations.These eleven populations include seven populations from east china sea(ES-1~ES-7),one from the yellow sea(SD)?one from The north Pacific(BT)?one from the north Taiwan sea(TW)and one from the west Africa(XF).1.Study on genetic dive rsity and population history of S.japonicus base on COI gene sequence analysis.A total of 27 mt DNA haplotypes and 34 variable sites were detected in the Mt DNA COI gene from 290 samples based on PCR amplified.The haplotype diversity(Hd)is 0.61396±0.02588 and nucleotide diversity(?)0.00196±0.00043.The genetic distances between the west Africa(XF)population and the other ten population is big ranging from 0.0121 to 0.0128,while the gene tic distances between the other ten populations is small ranging from 0.00080 to 0.0028.Pairwise Fst statistics suggested that(XF)population and the other ten population existed highest level of differentiation.Neighbor-joining(NJ)tree and median-joining(MJ)network analysis identified non-significant Phylogeographic structures.Molecular variance analysis(AMOVA)revealed that 58.74% of the genetic variation occurred within populations and 41.26% of the genetic variatio n occurred among populations.The expansion occurred in about 1,365,000 years ago,is in the late Pleistocene.2.Study on genetic diversity and population history of S.japonicus base on Cytb gene sequence analysis.A total of 64 mt DNA haplotypes and 90 variable sites were detected in the mt DNA Cytb gene from 288 samples based on PCR amplified.The haplotype diversity(Hd)is 0.73771±0.002408 and nucleotide diversity(?)0.00398±0.00056.The genetic distances between the west Africa(XF)population and the other ten population is big ranging from 0.02060 to 0.02120,while the genetic distances between the other ten populations is small ranging from 0.00080 to 0.00402.Pairwise Fst statistics suggested that(XF)population and the other ten population existed highest level of differentiation.Neighbor-joining(NJ)tree and median-joining(MJ)network analysis identified non-significant Phylogeographic structures.Molecular variance analysis(AMOVA)revealed that 51.28% of the genetic variation occurred within populations and 48.72% of the genetic variation occurred among populations.The expansion occurred in about 682,000 years ago,is in the late Pleistocene.3.Study on genetic diversity and population history of S.japonicus base on control region(D-loop)sequence analysis.A total of 131 mtDNA haplotypes and 113 variable sites were detected in the mtDNA D-loop sequence from 288 samples based on PCR amplified.The haplotype diversity(Hd)is 0.9608±0.0064 and nucleotide diversity(?)0.00398±0.00056.The terminal associated sequence(TAS),the central and conserved sequence block(CSB-F?CSB-E and CSB-D)and a variable domain(CSB-1,CSB-2 and CSB-3)are identified in the obtained sequence.The genetic distances between the west Africa(XF)population and the other ten population is big ranging from 0.0523 to 0.0539,while the genetic distances between the other ten population is small ranging from 0.0094 to 0.0160.Pairwise Fst statistics suggested that(XF)pop ulation and the other ten population existed highest level of differentiation.Neighbor-joining(NJ)tree and median-joining(MJ)network analysis identified non-significant Phylogeographic structures.XF group and other 10 groups divided into two groups.Molecular variance analysis(AMOVA)revealed that 77.19% of the genetic variation occurred among groups and 22.35% of the genetic variation occurred within populations.The expansion occurred in about 1,083,000 to 2,167,000 years ago in the late Pleistocene.4.Isolation and characterization of ten polymorphic microsatellites markers for the chub mackerel Scomber japonicus and cross-species amplificationIn this study,ten polymorphic microsatellite markers were developed in Scomber japonicus by RAPD-PCR methods.We detected 349 alleles.The number of alleles(NA)per locus ranged from 4 to 17.The observed and expected heterozygosity(HO and HE)per locus ranged from 0.2759 to 0.8621 and 0.43071 to 0.9177,respectively.The polymorphism information content(PIC)is from 0.3931 to 0.8939.Only one loci showed moderate polymorphism(0.25<PIC<0.5),while the rest were highly polymorphic(PIC>0.5).Tow locus showed significant deviation from Hardy-Weinberg equilibrium after Bonferroni corrections(p<0.005).N ine novel polymorphic microsatellite loci of S.japonicus could effectively amplify in the closely related species(S.australasicus).These markers will provide a useful tool for investigating the genetic structure,gene flow,species identification and fishery resources protection of S.japonicus and closely related species.5.Study on genetic dive rsity and population history of S.japonicus base on microsatellite analysis.We utilized nine polymorphic microsatellite makes to detect the genetic diversities of ten S.japonicus population.151 alleles are determined among ten S.japonicus populations.The highest average allele is SD population(Na=10.33),and the lowest is TW population(Na=6.00).The average observed heterozygosity(Ho)of ten S.japonicus populations is less than the average expected heterozygosity(He).The alleles per locus were 11-26 alleles,the average observed heterozygosity(Ho)range from 0.4443 to 0.7658.The average expected heterozygosity(Ho)range from 0.6844 to 0.7801.The average polymorphism information content of eight populations range from 0.854 to 0.879,and 80% of the combination doesn't deviate from Hardy-Weinberg equilibrium.Fst and UPGMA cluster analysis identified non-significant Phylogeographic structures,SD and ES-1 clustered into one group as well as ES-6? ES-7and BT clustered into one group in spite of the geographical distances is very far.Molecular variance analysis(AMOVA)revealed that 96.55% of the genetic variation occurred within population and 3.45% of the genetic variation occurred among populations. |
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